In the case of grinding rolls which are used in particular for so-called material bed comminution the problem of high wear on the roll surface arises. It is therefore known to counteract this wear by different shaping and coating of the roll surfaces exposed to the wear. A grinding roll is known from EP-A-0 516 957 in which pin-shaped profiled bodies are disposed on the roll surface, wherein only part of each profiled body is embedded in the basic roll body whilst the remaining part projects like a spine out of the basic roll body. The individual profiled bodies are spaced so that during operation some of the material to be comminuted becomes embedded in the interstices and thereby forms an autogenous wear protection.
In EP-B-0 659 108 a roller press is disclosed in which the roll surface is formed by flat zones which are made from highly wear-resistant material, the interstices between the highly wear-resistant zones being filled with a material having a different wear resistance. The interstitial material is a composite material which can be sintered and the highly wear-resistant zones are formed by hard bodies produced by hot-isostatic pressing, wherein the interstitial material and the material of the wear-resistant zones are fixed on the basic body by a hot-isostatic pressing operation and wherein the wear resistance of the interstitial material is basically slightly higher or lower than the wear resistance of the hard bodies in accordance with a desired profiling which is established due to wear.
Due to the measures described above, the wear on the roll surface could be reduced to an acceptable amount. However, the previously known measures do not constitute sufficient protection for the edges of the rolls or in the case of large rolls cannot be effected or cannot be effected economically, so that it is extremely difficult to introduce the material bed roll mill into the copper/gold industry because of the high wear on the roll surface. In the past the regions of the roll edges were protected by a hard-facing. However, the wear resistance was not sufficient and necessitated frequent re-welding of the rolls in this region. Depending upon the intensity, the service life of the rolls lasts for approximately 2 to 6 weeks, which drastically reduces the availability and involves high repair costs.
The object of the invention, therefore, is to provide a new concept of wear protection for the roll surface.